Posted
by
samzenpus
on Wednesday April 09, 2008 @08:25PM
from the two-possibilities-one-great-reality dept.

esocid writes "Until very recently, asking what happened at or before the Big Bang was considered by physicists to be a religious question. General relativity theory just doesn't go there — at T=0, it spews out zeros, infinities, and errors — and so the question didn't make sense from a scientific view. But in the past few years, a new theory called Loop Quantum Gravity (LQG) has emerged. The theory suggests the possibility of a "quantum bounce," where our universe stems from the collapse of a previous universe. This may be similar with beliefs of Physicist Neil Turok of Cambridge University who has theorized about a cyclic universe, constantly expanding and compressing."

There are different kinds of intelligence. Some people can solve complicated problems like getting laid but can't handle simple problems like calculating pi to 15 places using a couple of paper clips a rubber band and a slinky. This doesn't make them useless to society, and I think we should celebrate our differences.

To look at it another way, Einsein supposedly intuited a lot of his work and then proved it later. He had that kind of mind. If Einstein had been a goat herd 2000 years ago, the accepted mode of proof would have been vastly different, so proof from them rates as primitive religion now just as general relativity is the superstitious mumbo jumbo of the future. I'd take you in my time machine to prove it, but it only seats one and I know you're prone to not returning them... or will be on July 12th, 2017.

Also, Einsein was wrong about a whole lot of stuff, but that doesn't make his contribution useless. Ditto for the goat herders.

If someone does finally work it out, kill him. Until then, being open to the idea that someone who can't read or write but can play world class lawn bowls probably has as much, if not more insight into the true nature of nature than Hawking et al is a healthy perspective.

Considering approximately 5% of Physicists in the Unites States are religious

Every physicist I've ever met adheres to the cosmology of one religion or another, if only by way of personal suspicion about what science cannot answer.

And those friends of mine who have worked with far more physicists report that they often find fundamental reason for what is essentially religious belief in their work. You know, kind of like Einstein, who was "religious" in the sense that he believed in a fundamental and purposeful (deterministic) order, rather than the stark random chance esposed by th

Science and religion don't have to be mutually exclusive. It is entirely possible for God to obey the laws of physics (or create them, for that matter). Arguments about whether this theory or that law proves or disproves the existence of God are stupid - for example, it is possible that God decided to create man through evolution.I, too, know many scientists who are actively religious. Most of them say things along the lines of "my studies in field X have opened up to my mind the glory of God" or "the un

i think the conflict arises when science contradicts the particular holy texts of a religion, rather than the notion of a god. But that is only really a problem for biblical literalists or their equivalents, which from what you've said, i assume you aren't one of.

That in and of itself is only a problem when people blindly follow a particular translation of their holy text rather than try to discern what the true meaning of the text was in its original language. For example, to understand the prophecies of Isaiah, one must understand Jewish culture in the time of Isaiah. To understand the Mosaic Law, it is highly useful to understand the world at the time of Moses. And so on and so forth.Many people forget that, and they assume that their version of the Bible is c

God is just a meme that people get infected with. The first job of the meme is to protect itself from destruction, in fact religion is the definition of a successful meme. Its hardly surprising that we can reconcile anything from cosmology with religion. It would be a pretty crap religion if it couldn't worm its way into compatibility in our heads.

This is wrong. Science is the complete counter-point to religion. Your argument about a "god" creating the laws of physics IS a way to keep a "god". Evolution doesn't need a "god" to work and there are infinite possibilities of how the laws of physics could work.There is also the simple point that if the laws of physics worked a different way, we wouldn't be here to talk about them working the way they do, but because they work this way in this universe, we are here and have the option to create magical

If God could somehow manipulate the probability that this will occur, then any number of things are possible, including what we might think is "magic". Turn water to wine? Sure, just add the right particles to the water in the right proportions.

This is a perfect example of junk thinking. You start out assuming something and then use it to base other statements on that. Do you have any evidence that "god" can manipulate these probabilities? If not then the rest of your statement is really worthless.

Yep, I see many posters here being confused by the term "religious", which is rather vague.Some people take it to be the antonym of "atheist", while others take it to mean "a follower of a specific organized religion". When the OP said that 5% of physicists are "religious", did he mean that they follow an established religion, such as Methodists, Baptists, Catholics, Hindus, etc., or did he mean they were simply Deists, believing in some type of god but not being committed to any particular belief system a

Considering approximately 5% of Physicists in the Unites States are religious I dont think they considered it a religous question.

By "religious question", they mean, "according to our current understanding of the laws of physics, it is impossible, even in theory, to generate a falsifiable hypothosis about what happened before the big bang. Therefore, any discussion of what happened 'before' cannot be scientific, and hence is religions/philisophical discussion, not science".

TFA is about some folks claiming "actually, we DO have a hypothosis that is, at least in theory, falifiable".

"Science" is about studying things that are measurable, empirical, and/or falsifiable, whether one beleives that's ALL there is in the universe or not. "Religion" includes things that are not always empirical and falsifiable, and that cannot, even in theory, be scientifically tested. "Philosophy" includes all of the above and then some.

Whether something is or is not science, and whether something is or is not real, are two seperate questions-- whether or not one feels both questions have the same answer.

Exactly. I expect that if we could look into the moments immediately prior to the Big Bang, we'd see a bunch of scientists flipping a switch on the highest energy particle-accelerator of their universe.

Galactus, the Overmind, and the Stranger all came from the previous Universe, by one mechanism or another surviving the Big Crunch and the following Big Bang. There may be other previous universe types, but those 3 are the only ones I picked up on, back in my comic book days. (decades ago, even)

Correction: Galan was the sole survivor of the previous universe, and was reborn Galactus. Death and Eternity are his "siblings", the similarly reformed instances of the former incarnations of life and death. Which is odd since he lives inside Eternity, and converts life into death to extend his own life...

I bow to your superior knowledge of the Marvel Universe. Besides, my post was based on 30-40 year old memories. Did you ever stop to think that John McCain is the one Presidential candidate who can't make the "senior moment" joke over a memory lapse?

I apologize for any offensive if any was taken. My knowledge was based on 25 year old memories that have been continuously refreshed since I don't have a wife to throw out my comics or MSH role playing paraphernalia.;-)...:-/...:-(

No offense taken. I was just trying to make a Slashdot-ready phrasing for a response.I kind of drifted out of the Comics somewhere in high school, though I still have a few old ones laying around. (Including the "Batman vs Hulk" DC-Marvel crossover.) I also bought about a half-dozen Superman comics around the "Death of Superman" timeframe, just in case they gain collectors' value. Cheap investment, along with my 2 boxes of "Original Color" and 1 box of "New Wave" color Crayola 64-packs. (I bought the "

The main difference between a ten-year-old's idea and a solid scientific theory is very simple: math.Anyone can come up with all sorts of "it sounds logical" ideas but until you can back that idea with solid theory and mathematics all you have is wild conjecture. This idea of "twin" universes is based on a theory called Loop Quantum Gravity [einstein-online.info] which has made several important observations about the universe and has a very solid mathematical backing.

Depends on if you count the Harappans (~5500 B.C.E.) as Hindus, or maybe just the Classical Era populations (~1500 B.C.E.), or if you think it all starts with the Rig Veda (~1700 B.C.E.). It's tricky to say when what we call Hinduism today actually arose from earlier regional faiths.

By the way, we're on the 5109th year of the Hindu calendar, but that's debatable due to local variations.

There's nothing particularly special about loop quantum gravity that makes it possible to avoid having a singularity at the big bang. Loop quantum gravity is just one theory of quantum gravity. The best known theory of quantum gravity is string theory. In pretty much any theory of quantum gravity, the classical picture of the big bang singularity is going to get heavily modified. The conditions of the big bang are pretty much the only conditions under which you really need a theory of quantum gravity (unless you're really clever about finding some other situation, like black hole evaporation, where quantum gravitational effects come in). In all theories of quantum gravity, there's a scale called the Planck scale, and when you go beyond that scale (e.g., the universe is hot enough so that the wavelengths of particles are on the order of the Planck length), mysterious stuff happens. Because of this, it's reasonably plausible that the big bang singularity is eliminated in any theory of quantum gravity.

Old attempts to make a theory of a rebounding big bang (with, e.g., a cyclic universe) had various technical problems, which have been solved in recent years. In a rebounding big bang, there are issues to worry about such as what happens to causality, entropy, and the thermodynamic arrow of time. E.g., you could imagine that a universe cycles through a series of big bangs, and that each cycle is a lot like the one before, or you could imagine that the second law of thermodynamics operates across rebounds, so that each cycle has more entropy than the one before. You could imagine that there could be cause and effect relationships extending across rebounds, or that that could be prevented by the laws of physics. Some people believe that there's an unsolved "entropy problem" in the current standard big bang theory. Here [princeton.edu] is a good FAQ about cyclic models.

Actually there IS something special about loop quantum cosmology - it's theory actively predicts a big bounce instead of a big bang. This comes directly out of the loop quantization of a homogenous and isotropic cosmology. So far all other theories have had to put in a bounce "by hand" - adding extra physics at the singularity in order to get something out of the other side. LQC doesn't do that - it replaces the usual metric and curvature operators with holonomies and flux operators as done in loop quantum gravity (OK, the derivation isn't exact yet, and we've a lot more work to do here).

Once you do this, however (and by using other tricks like using a massless scalar field as your time variable), you see that a contracting branch naturally re-expands once you reach a critical matter density (something like 82% of the Planck density - Ashtekar has a good numerical reason for this IIRC). In these steps you end up replacing the Wheeler-deWitt equation (a continous differential equation) with a difference equation which needs to pick a certain super-selection sector of the theory - in simpler terms the timestep effectively becomes discrete.

The beauty of LQC is that it doesn't need us to speculate about what happens at singularities - it gives us an active way to look at them without needing to invent new physics that only apply there. Sure, it makes a few assumptions - that our basic observables are holonomies and fluxes - but there's no new input directly at the singularity, unlike in other theories (such as ekpyrotic scenarios where two branches are joined artificially across the singularity.

If you have questions, please reply and I'll see what I can do to answer them to the best of my ability. If there's enough interest, I might be able to get an "Ask Slashdot" type of thing put to Ashtekar/Bojowald although it'll probably be their post-docs and grad students who end up answering all the questions;)

While you guys go off on quantum loop tangents,
we're still trying to work through some 19th century problems like the Riemann hypothesis! Your latest theories aren't scheduled to be made rigorous until
2158 at the earliest.

Incidentally, string theory ALSO predicts a kind of rebounding universe. IIRC it seems that in ST a universe with a radius of R is indistinguishable from a universe with a radius of 1/R, when measuring R in Plank lengths.

Though coming from very different directions, both LQG pioneer Lee Smolin [leesmolin.com] and Stephen Wolfram [stephenwolfram.com], who needs no introduction here, have opined that the best candidate as the fundamental level of a discrete physics (i.e. where the appearance of being continuous is emergent) is a graph theoretic network of nodes and links where it ceases to make sense to ask what they are made of. (This is also explored in Greg Egan's Schild's Ladder [gregegan.net].) The basic idea is that there is some simple enough but cosmologically consistent transformation rule which produces the next local state of the graph from the current local state, supposedly at the Planck scale [unsw.edu.au] (of order 10^43 times per second).

A likely scenario is that "somewhere" long unreachable beyond our event horizons, there was a region of network sustaining chaotic inflationary expansion in which a bubble of more conservative physics emerged. Our conservative bubble only exhibits polynomial (near cubic) growth but that was enough to separate it from the exponentially growing seed graph.

My current betting is that Type 1a Supernovae [wikipedia.org], or at least some more precise analogue thereof in our parent cosmos, seed new outbreaks of chaotic inflation in which a new generation of more conservative bubble cosmoses arise, the whole process being susceptible to selection for fecundity and constrained only by the need for a viable history to some initial conditions simple enough to have just happened, presumably for no better reason than because nothing is unstable.

First, we will likely never prove anything at the Planck scale. This means that without some radically better ideas, we may be stuck with current situation -- lots of theories but no proof.

Second, one cannot take a theory that is wrong in a measurable way, make some small adjustment, and end up with a theory that is right. In field theory if we get the strength of electromagnetism wrong, we can adjust it. It's just a number. If we find a new particle we didn

In David Brin's book "Earth" it is suggested by a scientist, that in the moment of the collapse of an experimentally created black hole, it separates itself from this universe (like the separation of a child from its mother) taking with it all consumed energy which lies behind the event horizon. In his speculation the implosion of a singularity in this universe is followed by an explosion/expansion of a singularity in the child-universe, which then became independent of ours. Of course this causes an energetic underpressure with every collapse of a black hole, finally making this universe disappear when the last singularity implodes. It can be interpreted as a variant of the oscillatory universe theory.

What if the big bang was just the explosion of all the crap that was in the event horizon of a black hole from a parent universe?

Questions I have are:-How could there be such a massive black hole in a parent universe that our universe originated from? Subsequent universes would have smaller and smaller total mass/energy so it couldn't go on forever, and that would mean there was a starting point?-Wtf is the collapsing of a black hole? I thought they evaporated...

Last time I followed this stuff. The universe was open (destined for heat death) and the margin of "how open" was HUGE.Unless the universes before had significantly different masses, there's no way this happened.

It's irrelevant in any case. You can think, talk, have a beer while imagining all this stuff as much as you want. But unless you can tack a method of gathering data to TEST the theory it IS. NOT. SCIENCE.

This is the great danger that intelligent design poses to the U.S., according to Ken Miller. By trying to put the supernatural into science, it turns all of science into just another belief system, causing many to call evolution and global warming a "religion".

Of course. If there's a long series of 'big bangs' followed by 'big crunches' etc... Then it would just follow that there was a previous 'universe' that underwent a big bang/big crunch cycle, one before that, and probably one after ours crunches down then explodes again to creat another 'universe'.

Yes, it will crunch down again because gravity always wins, even against Chuck Norris.

How exactly would this answer a religious question again? It still doesn't answer the question of where the Universe came from in the first place nor why it came about nor... I mean seriously, replacing a "We don't know" with the equivalent of "It's turtles all the way down" doesn't exactly answer any so called religious questions at all. In fact, it doesn't even encroach on them.

You are assuming that the scale of space is stable - that the separation of galaxies comes entirely from their material moving apart (at sublight speed) since they were essentially together in the moments after the big bang.

In fact space itself stretches. The separation of the material between pairs of distant (and near) galaxies comes from both their motion through space and the stretching (expansion) of the space between them.

The result is that sufficiently distant galaxies can be much farther apart than they could have traveled - even at the speed of light - through non-expanding space in the time since the big bang.

If space (and in effect time) stretched like that, it wouldn't even matter. It would be like stretching a gummy bear... sure, maybe you got a long gummy bear, but it is still ONE gummy bear. If space stretched, so would time, and one unit of space-time is one-unit of space-time, regardless.

To use your analogy, draw a grid on the balloon. When you inflate the balloon, the grid squares grow. But one unit is still one unit. If you had to measure around the balloon, it would be x squares, regardless the size. This is because we are IN the balloon so that is our frame of reference. You are measuring it outside of the universe, and it just doesn't work like that.

You are pointing to imperfections in an analogy and claiming they are flaws in the concept the analogy is meant to describe. The balloon analogy is not a premise supporting expansion. It's just a visual aid.

This is because we are IN the balloon so that is our frame of reference.

No, we are on the balloon. The surface of the balloon is a 2D representation of our 3D space. Talking about the inside of the balloon is nonsensical.

No, we are on the balloon. The surface of the balloon is a 2D representation of our 3D space.

You are trying to oversimplifying it and it is getting in the way. The balloon is our universe. Drawing a grid on the outside would be akin to cubing up a block of cheese. Get past the fact that it is drawn on a 2d surface. This represents cubes of space/time [wikipedia.org] within our universe.

In the end, the change in distance is offset by the change in time, which makes it a non-issue.

So it would be safe to say that if nothing can travel faster than the speed of light, we could witness objects
distancing themselves at almost 3 times the speed of light, considering the addition of each:
- object A can travel "just a bit slower" than the speed of light in one direction
- space can stretch "just a bit slower" than the speed of light
- object B can travel "just a bit slower" than the speed of light in opposite direction from object A
Interesting isn't it?

Unfortunately, you can't do simple addition when you're dealing with relativistic velocities. The details of the math are beyond me, but in essence: velocity is a defined distance traveled over a certain amount of time. And, under relativity, time is not constant.

Consider having two probes going away from Earth at 60%-lightspeed in opposite directions, and they want to communicate with each other. At 120%-c speeds, you might think it's impossible. But each of them could communicate back and forth with Earth at mere 60%-c speeds. If you do the actual math you work out that they appear to each other as moving away at something-like-80%c (that figure is totally made up, but you should get the idea anyway).

So it would be safe to say that if nothing can travel faster than the speed of light, we could witness objects distancing themselves at almost 3 times the speed of light, considering the addition of each:...

Nope. You can't observe objects whose effective speed in your reference frame - combining inflation with velocity - is greater than C. The light from them never reaches you and light from you can never reach them. From your point of view they're "off the edge". It's as if you and they were each below the event horizon of a black hole relative to each other.

(And sorry about an error in my previous post. The correct buzzword for the stretching of space is "inflation".)

Well, if we can't make observations about such physical phenomena as space expanding faster than the speed of light, then isn't it pointless to discuss such phenomena from the standpoint of physics? If we can't make any observations to confirm a model then it's pointless to develop the model except as an exercise in mathematical reasoning.Oh, and buzzword isn't the same as a precisely-defined technical term. For a good litmus test, compare the precision of the definition of "Web 2.0" to the definition of "F

Observations to support a model may not be immediately apparent, but there can be indirect evidence. Development of a given model may provide a framework for other models, some of which provide opportunity for observational evidence. Observational support for a derivative model may provide indirect support for supporting models. It's certainly not as good as direct support, but absent evidence to the contrary, it's better than essentially only mathematical support, which has caused some theories such as

You can see objects whose effective speed is greater than c _now_, but wasnt when the light was emitted. We can see objects with a redshift equal to that of an object travelling twice or more the speed of light. (Redshift of about 6 ish)

If object B looked back at object A, B would see A moving away from it slower than the speed of light due to time dilation. Time isn't actually any different for A than for B or for you in the center because you're not supposed to say that any one of them is actually the one that's moving. So if you're sitting in the center waving your hand at second intervals, B and A would see you waving very quickly. Likewise if I'm at B waving my hand at 1 second intervals you in the center would see my waving as qui

But CMB fills the entire universe, it doesn't come from one localized area. See the part of his post:

What you want is a specific "point" at which the big bang happened. That's not the case. When it happened - it WAS the universe - ie it was every single point at once. As the universe expands - anywhere you look from or to you'll be able to see this background radiation. Of course there will be fluctuations if the expansion of the universe isn't completely uniform - and why should it be? Matter distorts space and time, contributing to this non-uniformity.

Actually, CMB is not from the Big Bang, but from the "recombination" event about 400,000 years after the Big Bang. That's when the universe changed from cloudy to clear, and the light in the universe was suddenly free to travel in straight lines. But again, this event took place all over the universe at the same time, therefore we see the radiation coming from all directions. At this time, the universe was nearly uniform (to one part in 100,000), so the radiation is nearly uniform in all directions.

We DO "see" the remnants of the big bang. It's the nearly uniform 3K cosmic background radiation. That's what happens when you take an imensely energetic ball of stuff and stretch it to the current size of the universe.

OK, I'm not a cosmologist. The Big Bang is a theory so could certainly be wrong, so I'm posing a question here as well as posing a 'what if?'. We're looking for the God Particle (Higgs boson), which attaches itself to all matter except photons. Well, I think they attach to photons in some way too. Where I'm going is to a steady state universe where the most distant light has been affected by Higgs' particles. That light has lost energy getting here though not velocity. We see it as a red shift. Furt

but wait... if 2 people leave my house at lightspeed in opposite directions, after an hour they will be at 2 lighthours from each other ! so they would have to be already travelling 2 hours after that hour ?

Your mistake is thinking that time and space are constants. They are not. They are relative to your reference frame. Hence the name relativity. After one hour, the two people are two light hours apart from each other from your reference frame. From their reference frame, time is going slower and distances in the directions they are traveling are shorter, so they would not measure themselves as being two light hours apart. They would measure themselves as being no more than one light hour apart, although fro

If I leave your house traveling at the speed of light, and look back an hour later, I'll see your house exactly as I left it. (Pretending that time would actually pass enough for me to 'see' anything.)

So, 'relatively', anyone who also left at the same time, in any direction, at any speed, looks like they're 'relatively' an hour away! Because they're standing at my starting point motionless!

Of course, as no one can actually do anything at the speed of light, even

Bush wasn't president of the U.S and we now have people on Mars and so on. That universe had Al Gore as president.

Ah, I see. Because... when Gore and Clinton were in charge of NASA, there were plans in place and programs under way to have people on Mars by now, only 7 years later, and that got stopped cold by Teh Evil Bush. I wonder what else was under way while Clinton and Gore were running the executive branch? Say, the rapid build up of Al Queda tranining camps in Afghanistan, and the launching of pla

You forgot to mention the whole carbon footprint of launching something big enough to colonize Mars... something that would probably make Gore have an aneurysm.

Yeah, but then again, you're assuming he actually believes the stuff he spouts off, b/c in this universe, he refuses to debate ANYONE on the facts, and he owns the companies he buys 'carbon credits' from... weird, huh?

Actually, you are trolling. Being right-winged loser how lives in your moms basement

I keep looking at your reply, knowing that somewhere in there you'll point to how exactly President Gore would have had us on Mars by now. You must be really, really subtle, because I'm not seeing it. Or, maybe you're just full of crap on that subject, and were making a comment that is the very definition of a troll. Now, which part was I wrong about? Afghanistan? The recession that started in 1999? See, I can point at yo

We'd probably be a lot closer to Mars, or some other notable space endeavor, right now if Gore had been elected in 2000, simply because we never would have been distracted by Iraq and wasted so much time and money there. We probably would have gotten involved in Afghanistan because of Al Qaeda, but that's taken far less money and effort than the Iraq boondoggle, which had nothing whatsoever to do with Al Qaeda.Unfortunately, we'd probably have gotten much stricter gun laws too under Gore, and increased cri

I'll admit that I don't know what he's talking about. But it's not really a unique theory, in that there are other "fate of the universe" theories that predict that an end of one universe will bring the beginning of another. Or something along those lines. I had a lecture recently, where the professor talked about some of the wildly speculative theories of the future of the universe. It goes something like the following:

The common view now is that the expansion of the universe is accelerating [wikipedia.org]. As the universe ages, galaxies will be spread further away, and the amount of hydrogen and helium in any given galaxy will start to decrease to the point that it would be difficult to produce any stars. Galaxies will be full of brown dwarfs, white dwarfs, and black holes. Over a long time frame, galaxies will start shedding some of their stars, and black holes will decay via the process of Hawking radiation [wikipedia.org]. Eventually, about a googol years from now, protons will start to decay [wikipedia.org]. As the universe runs out of ways to generate energy, there will be parts of the universe, starting with the large empty gaps left behind by the expansion, that will undergo a phase transition. Once some pockets of the universe undergo phase transition, they will act as seeds that spread the transition to other parts of the universe (like the process of water turning into ice). When the phase transition is complete, the laws of physics will change drastically, and there may be a new seed for a new universe.

As I mentioned earlier, it's WILDLY speculative, so don't take this comment as anything definitive. I just wanted to illustrate one of the many theories out there that share some of the most basic premises of the one in the story.

It's not a new definition or a redefinition. You just aren't familiar with the standard terminology used by physicists. That's okay, no one mistook you for a physicist in the first place. There are far more phase transitions [wikipedia.org] than the ones you are likely to be familiar with.

I gave you a link that shows experimental data. And there is no such thing as empty space, it's a froth of virtual particles. That's why the Casimir effect exists. But look, I don't want to go explaining all of modern physics to you. Ther

I was going to say that twins are an impossible fantasy and you might as well just have sex with the same woman twice, but then I realised that around here "sex", and indeed "woman", are also impossible fantasies.

Our galaxy will continue to merge with other galaxies around us, as has happened for the past several billion years. The expansion of space will push all other galaxies out beyond the limit of the observable universe. Hundreds of billions of years from now, astronomers in our galaxy will see only our galaxy and no others. Astronomers in other galaxies would similarly see only their galaxy. Scientific American had an article on this exact topic a few months ago.